The correct answer is "a secular ruler claimed the right to appoint bishops."
The Concordat of Worms resolved the disagreement over lay investiture, which was when a secular ruler claimed the right to appoint bishops.
What King Henry V did was to hold an assembly in Worms, Germany, and issued the Edict of Worms. After some negotiations, the king reached an agreement with Pope Calixtus II to end the conflicts regarding the investiture of the popes. The king accepted to allow free elections so bishops could choose the pope without the intervention of the Holy Roman emperor.